A bit of background first:
An SBS 2008 server went down with Hard Drive failure. Re-built and all now working. Customer was, however, concerned about interruption of emails if it happened again so migrated all emails to Exchange Online.
They now want to replace the Server and Server 2012 R2 Essentials has been decided as the best option.
I am aware that you can “tie-in” Exchange Online with User Accounts on Server 2012 Essentials and create & delete etc.
My question is:
Does the Server running 2012 Essentials have to be functional to log into Exchange online if the account is "linked"?
I remember, when migrating from SBS 2008 that I read you could do something similar but came to the conclusion that authentication to the email account took place on the server and, if the server wasn't running, you couldn't log in and get your email by whatever means – online, Outlook etc. Since the company moved to Exchange Online to avoid such an issue, I never went any further with it.
I was therefore wondering if this is the same for 2012 Essentials or whether the two can be looked after independently of each other when it comes to email and Office 365 as a whole.
A case of convenience rather than control...
Thanks in advance for your advice.